The role of computed tomography in assessing pleural malignancy prior to thoracoscopy

Imaging in pleural Mesothelioma: A review of the 16th International Conference of the International Mesothelioma Interest Group

Imaging continues to gain a greater role in the assessment and clinical management of patients with mesothelioma. This communication summarizes the oral presentations from the imaging session at the 2023 International Conference of the International Mesothelioma Interest Group (iMig), which was held in Lille, France from June 26 to 28, 2023. Topics at this session included an overview of best practices for clinical imaging of mesothelioma as reported by an iMig consensus panel, emerging imaging techniques for surgical planning, radiologic assessment of malignant pleural effusion, a radiomics-based transfer learning model to predict patient response to treatment, automated assessment of early contrast enhancement, and tumor thickness for response assessment in peritoneal mesothelioma.

Imaging in Lung Cancer Staging

Lung cancer remains one of the leading causes of mortality worldwide, as well as in the United States. Clinical staging, primarily with imaging, is integral to stratify patients into groups that determine treatment options and predict survival. The eighth edition of the tumor, node, metastasis (TNM-8) staging system proposed in 2016 by the International Association for the Study of Lung Cancer remains the current standard for lung cancer staging. The system is used for all subtypes of lung cancer, including non-small cell lung cancer, small cell lung cancer, and bronchopulmonary carcinoid tumors.

Staging by Thoracoscopy in potentially radically treatable Lung Cancer associated with Minimal Pleural Effusion (STRATIFY): protocol of a prospective, multicentre, observational study

INTRODUCTION

Recurrence rate following radical therapy for lung cancer remains high, potentially reflecting occult metastatic disease, and better staging tools are required. Minimal pleural effusion (mini-PE) is associated with particularly high recurrence risk and is defined as an ipsilateral pleural collection (<1/3 hemithorax on chest radiograph), which is either too small to safely aspirate fluid for cytology using a needle, or from which fluid cytology is negative. Thoracoscopy (local anaesthetic thoracoscopy (LAT) or video-assisted thoracoscopic surgery (VATS)) is the gold-standard diagnostic test for pleural malignancy in patients with larger symptomatic effusions. Staging by Thoracoscopy in potentially radically treatable Lung Cancer associated with Minimal Pleural Effusion (STRATIFY) will prospectively evaluate thoracoscopic staging in lung cancer associated-mini-PE for the first time.

METHODS AND ANALYSIS

STRATIFY is a prospective multicentre observational study. Recruitment opened in January 2020. The primary objective is to determine the prevalence of detectable occult pleural metastases (OPM). Secondary objectives include assessment of technical feasibility and safety, and the impact of thoracoscopy results on treatment plans, overall survival and recurrence free survival. Inclusion criteria are (1) suspected/confirmed stages I-III lung cancer, (2) mini-PE, (3) Performance Status 0-2 (4), radical treatment feasible if OPM excluded, (5) ≥16 years old and (6) informed consent. Exclusion criteria are any metastatic disease or contraindication to the chosen thoracoscopy method (LAT/VATS). All patients have LAT or VATS within 7 (±5) days of registration, with results returned to lung cancer teams for treatment planning. Following an interim analysis, the sample size was reduced from 96 to 50, based on a lower-than-expected OPM rate. An MRI substudy was removed in November 2022 due to pandemic-related site setup/recruitment delays. These also necessitated a no-cost recruitment extension until October 2023.

ETHICS AND DISSEMINATION

Protocol approved by the West of Scotland Research Ethics Committee (Ref: 19/WS/0093). Results will be published in peer-reviewed journals and presented at international meetings.

TRIAL REGISTRATION NUMBER

ISRCTN13584097.

Results of the Meso-ORIGINS feasibility study regarding collection of matched benign-mesothelioma tissue pairs by longitudinal surveillance

OBJECTIVES

To assess key elements of the design for Meso-ORIGINS (Mesothelioma Observational study of RIsk prediction and Generation of paired benign-meso tissue samples, Including a Nested MRI Substudy), an ambitious, UK-wide, prospective study that will collect ≥63 matched benign-mesothelioma tissue pairs through longitudinal surveillance and repeat biopsy of patients with asbestos-associated pleural inflammation (AAPI).

DESIGN

A multicentre, mixed-methods feasibility study, comprising a prospective observational element, evaluating recruitment feasibility, technical feasibility of repeat local anaesthetic thoracoscopy (LAT) and patient acceptability, and a retrospective cohort study focused on AAPI-mesothelioma evolution rate, informing sample size.

SETTING

4 UK pleural disease centres (February 2019-January 2020).

PARTICIPANTS

Patients with AAPI (history or typical imaging plus appropriate pleural histology) were eligible for both elements. In August 2019, eligibility for the prospective element was broadened, including addition of radiological AAPI for technical feasibility and patient acceptability endpoints only. Retrospective cases required ≥2 years follow-up.

OUTCOME MEASURES

A prospective recruitment target was set a priori at 27 histological AAPI cases (or 14 in any 6 months). Technical feasibility and patient acceptability were determined at 6-month follow-up by thoracic ultrasound surrogates and questionnaires, respectively. Retrospective malignant pleural mesothelioma evolution rate was defined by proportion (95% CI). Baseline predictors of evolution were identified using logistic regression.

RESULTS

296 patients with AAPI (39 prospective, 257 retrospective) were recruited/selected. 21/39 prospective recruits were histologically diagnosed (target n=27). Repeat LAT was technically feasible and acceptable in 13/28 (46%) and 24/36 (67%) cases with complete follow-up data. Mesothelioma evolution was confirmed histologically in 36/257 retrospective cases (14% (95% CI 10.3% to 18.8%)) and associated with malignant CT features (OR 4.78 (95% CI 2.36 to 9.86)) and age (OR 1.06 (95% CI 1.02 to 1.12)).

CONCLUSIONS

Our initial eligibility criteria were too narrow. Meso-ORIGINS will recruit a broader cohort, including prevalent cases, any biopsy type and patients with malignant CT features. A range of rebiopsy techniques will be allowed, accounting for technical and patient factors. The sample size has been reduced to 500.

TRIAL REGISTRATION NUMBER

ISRCTN12840870.

Different characteristics of pleural abnormalities on computed tomography between tuberculous and malignant pleural effusions

BACKGROUND

Computed tomography (CT) is the mainstay imaging modality for suspected pleural malignancy. Tuberculous pleural effusion (TPE) can present with various pleural abnormalities. However, few studies have evaluated the different characteristics of pleural abnormalities on chest CT between TPE and malignant pleural effusion (MPE).

METHODS

Pleural abnormalities on contrast-enhanced CT in 277 and 289 patients with confirmed TPE and MPE diagnoses, respectively, were retrospectively assessed and compared between the two groups. Discriminating factors and diagnostic performance for MPE were evaluated using multivariate analysis and receiver operating characteristic curves.

RESULTS

Focal pleural thickening was present in 44 (16%) cases of TPEs and 202 (70%) of MPEs. Further characterization of focal pleural thickening showed that MPEs had a significantly greater number, larger maximal thickness, and more nodular contour form, compared to TPEs. On the other hand, diffuse and circumferential pleural thickening were significantly more common in TPEs. In multivariate analysis, independent predictors for MPE included focally thickened pleurae ≥7, maximum thickness ≥6 mm, nodular contour pattern, and the absence of diffuse pleural thickening. Out of all the individual or combined predictors for MPE, the presence of any one of the three sub-parameters of focal pleural thickening provided the best diagnostic yield with 66% sensitivity and 92% specificity.

CONCLUSION

Although focal pleural thickening in TPE mimics that in MPE, the features of MPE are significantly different from those of TPE in terms of size, number, and contour. These different characteristics may help differentiate MPE from TPE in patients with suspected MPE.

Diffusion-weighted imaging diagnostic algorithm in patients with suspected pleural malignancy

Objectives

The purpose of this study was to analyze the diagnostic performance and clinical application of diffusion-weighted imaging (DWI) in patients with suspected pleural malignancy (PM).

Methods

A retrospective review of patients with suspected PM was performed from March 2014 to August 2018 (NCT 02320617). All patients underwent chest DWI and computed tomography (CT) with cytological or histopathological findings as reference standards. The diagnostic performance of DWI and CT was analyzed and compared. A DWI diagnostic algorithm with three sequential steps was established.

Results

Seventy patients (61.6 ± 13.6 years; 47 males and 23 females) were included. The sensitivity of DWI (94.2%, 49/52) for the diagnosis of PM was significantly higher compared with CT (67.3%, 35/52), with similar specificity (72.2% vs. 72.2%, respectively). The apparent diffusion coefficient of malignant lesions (1.15 ± 0.32 × 10⁻³ mm²/s) was lower compared with benign lesions (1.46 ± 0.68 × 10⁻³ mm²/s), but the cutoff value was difficult to define for overlap between groups. Approximately 62.5% (5/8) of invasive procedures were avoided when using the DWI diagnostic algorithm in patients with suspected PM without N3 lymph node or extra-thoracic metastasis.

Conclusion

Including DWI into the diagnostic algorithm of suspected PM can effectively identify malignancy and avoid unnecessary invasive procedures, which may have some potential in clinical application.

Key Points

• Diffusion-weighted imaging can identify pleural malignancy much more efficiently than CT.

• A diffusion-weighted imaging diagnostic algorithm helped to avoid unnecessary invasive procedures in patients without N3 lymph node or extra-thoracic lesions.

• A hyperintense signal on DWI at a high b value (800 s/mm²) but not at a low b value (50 s/mm²) was a reliable signature of PM.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08013-6.

Diagnostic role of medical thoracoscopy in childhood pleural tuberculosis

Currently, the diagnostic role of medical thoracoscopy in childhood pleural tuberculosis remains uncertain. Therefore, this retrospective study was conducted to evaluate the diagnostic performance of histological examination of tissue samples obtained by medical thoracoscopy in childhood pleural tuberculosis. Hospitalized children who underwent medical thoracoscopy between May 2012 and March 2016 were included in the study. Tissue samples obtained by thoracoscopy were submitted for histological examination (hematoxylin and eosin staining). Descriptive statistical methods were used for data interpretation, and the data were expressed as the mean ± standard deviation. The childhood tuberculosis patients had the following characteristics: 11 had pleural tuberculosis and 9 had pleural tuberculosis + pulmonary tuberculosis, the average age was 13.0 ± 2.2 years old, 60% were male, 26.3% (5/19) of patients tested positive for acid-fast bacilli positive in smears, 21.1% (4/19) of patients were positive for TB-PCR, and 90% (18) of pleural tuberculosis patients were positive in the culture for Mycobacterium tuberculosis. The sensitivity of histological examinations of tissue samples obtained by thoracoscopy in the detection of pleural tuberculosis was 80% (16/20). Complications were reported in 15 cases, and all complications disappeared spontaneously without any specific treatment. Therefore, we concluded that medical thoracoscopy was a sensitive and safe tool for the detection of childhood pleural tuberculosis.

Comparison of cytology, chest computed and positron emission tomography findings in malignant pleural effusion from lung cancer

Background

Malignant pleural effusion (MPE) is a common medical problem in lung cancer (LC). Pleural fluid cytology (PFC), chest computed tomography (CCT) and positron emission tomography (PET) findings are helpful as first line approach. The objectives of this study were to evaluate whether there is a correlation between PFC, CCT and PET in patients with MPE due to LC.

Methods

We selected patients from our electronic files. Data of PFC, pleural biopsy (PB), CCT and PET have been recorded and analyzed.

Results

A total of 101 consecutive patients (66 males, 65.3%) with a mean age of 66.2±31 years were selected. Types of LC were adenocarcinoma in 71 patients (70.2%), squamous in 13 (12.8%), small-cell in 12 (11.8%) and large cell in 5 (4.9%). CCT showed nodules in 6 (5.9%), pleural thickening in 8 (7.9%) and both in 17 (16.8%) patients. PFC was positive in 55/91 thoracentesis (60.4%) and 32/52 thoracoscopy (61.5%), while PB in 38/40 performed (95%). PET fixation was found in 32/47 (68%) patients who had MPE at diagnosis. When we associate PFC to CCT and PET findings, the yield in our study becomes 90%. No correlation was observed between CCT findings and PFC (P=0.62) between PFC and PET fixation (P=0.63) or between CCT and PET (P=0.06).

Conclusions

In our cohort of LC patients with MPE, we observed a high sensitivity for PFC, while in most of the cases no findings were observed in CCT. PET had a relative low sensitivity. However, when all 3 methods were combined the yield was 90%.

(F)utility of computed tomography of the chest in the presence of pleural effusion

BACKGROUND

Pleural effusion is common and can cause significant morbidity. The chest X-ray is often the initial radiological test, but additional tests may be required to reduce uncertainty and to provide additional diagnostic information. However, additional exposure and unnecessary costs should be prevented. The objective of the study was to assess the clinical benefit of an additional chest computed tomography (CT) scan over plain chest X-ray alone in the management of patients with pleural effusion.

METHODS

Retrospective analysis in 94 consecutive patients with pleural effusion who underwent chest X-ray and CT scan over an 18-month period in a single institution. All chest X-ray and CT scan reports were compared and correlated with clinical parameters in order to assess their utility in the clinical management. No blinding was applied.

RESULTS

In 75 chest CT scan reports (80 %), information provided by the radiologist did not change clinical management when compared to plain chest X-ray alone and did not provide any additional information over chest X-ray. Only 2/49 (4 %) of the native chest CT scan reports provided clinically relevant information as compared to 17/45 (38 %) contrast-enhanced chest CT scan reports (p<0.001).

CONCLUSIONS

In this retrospective cohort of patients with pleural effusion, an additional chest CT scan was not useful in the majority of patients. However, if a chest CT scan is required, then a contrast-enhanced study after pleural aspiration should be performed. Further prospective studies are required to confirm these findings.

State-of-the-art: Radiological investigation of pleural disease

Pleural disease is common. Radiological investigation of pleural effusion, thickening, masses, and pneumothorax is key in diagnosing and determining management. Conventional chest radiograph (CXR) remains as the initial investigation of choice for patients with suspected pleural disease. When abnormalities are detected, thoracic ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) can each play important roles in further investigation, but appropriate modality selection is critical. US adds significant value in the identification of pleural fluid and pleural nodularity, guiding pleural procedures and, increasingly, as "point of care" assessment for pneumothorax, but is highly operator dependent. CT scan is the modality of choice for further assessment of pleural disease: Characterising pleural thickening, some pleural effusions and demonstration of homogeneity of pleural masses and areas of fatty attenuation or calcification. MRI has specific utility for soft tissue abnormalities and may have a role for younger patients requiring follow-up serial imaging. MRI and PET/CT may provide additional information in malignant pleural disease regarding prognosis and response to therapy. This article summarises existing techniques, highlighting the benefits and applications of these different imaging modalities and provides an up to date review of the evidence.